In dispensing fluids such as pressurized gas from pressurized vessels, a number of mechanical devices are frequently employed to facilitate controlled and safe operation of the system. Typically these mechanical devices include a regulating mechanism to allow control over the pressure at which the fluid is dispensed, an over-pressure relief device to maintain safety of operation, and usually two pressure gauges, one gauge indicating the pressure within the pressure vessel and the second gauge indicating pressure on the other side of the regulating valve, i.e., line pressure. Previous apparatuses for performing these various tasks have often involved complex mechanical configurations, bulky appendages, and fragile parts.